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ExploitedIn CISA KEVFix available

CVE-2023-27351

Exploitation confirmed. First attested on 2026-04-18 by CISA-ADP, CISA KEV, GCVE · kevintel, GCVE · shadowserver.

  • Published2023-04-20
  • Fixed in22.0.9 · 21.2.11 · 20.1.7
  • WeaknessCWE-287

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

This vulnerability allows remote attackers to bypass authentication on affected installations of PaperCut NG 22.0.5 (Build 63914). Authentication is not required to exploit this vulnerability. The specific flaw exists within the SecurityRequestFilter class. The issue results from improper implementation of the authentication algorithm. An attacker can leverage this vulnerability to bypass authentication on the system. Was ZDI-CAN-19226.

Timeline

dates in UTC
  1. 2023-04-2016:15CVE publishedNVD
  2. 2026-04-1800:07Listed as exploited by GCVEGCVE
  3. 2026-04-1800:07Exploitation first reportedGCVE
  4. 2026-04-20Added to the CISA KEV catalogCISA KEV
  5. 2026-04-2103:55SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-04 09:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2023-27351?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2023-27351?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Papercut papercut mf
BranchAffectedFixed in
22.0≥ 22.0.0, < 22.0.922.0.9
21.x≥ 21.0.0, < 21.2.1121.2.11
20.1≥ 15.0, < 20.1.720.1.7
Papercut papercut ng
BranchAffectedFixed in
22.0≥ 22.0.0, < 22.0.922.0.9
21.x≥ 21.0.0, < 21.2.1121.2.11
20.1≥ 15.0, < 20.1.720.1.7

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As zdi, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • PaperCut NG
    Affected
    • = 22.0.5 (Build 63914)no fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2023-04-20

Fix

  1. Update Papercut papercut mf to 22.0.9 · 21.2.11 · 20.1.7
  2. CISA’s required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.due 2026-05-04

Advisories and patches

Detection

read 2026-11-03 22:42 UTC
Nuclei template
available
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

CISA Known Exploited Vulnerability

Date Added
2026-04-20
Patch Due Date
2026-05-04
Ransomware Use
Unknown
Required Action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Published
2023-04-20
Last Modified
2026-10-01
NVD status
Analyzed
GitHub Advisory
GHSA-2c69-r2jh-xjvm

Frequently asked questions

What is CVE-2023-27351?

This vulnerability allows remote attackers to bypass authentication on affected installations of PaperCut NG 22.0.5 (Build 63914). Authentication is not required to exploit this vulnerability. The specific flaw exists within the SecurityRequestFilter class. The issue results from improper implementation of the authentication algorithm. An attacker can leverage this vulnerability to bypass authentication on the system. Was ZDI-CAN-19226.

Is CVE-2023-27351 actively exploited?

Yes. CVE-2023-27351 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2026-05-04.

What is the CVSS score for CVE-2023-27351?

CVE-2023-27351 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

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